The art knows of devices for the manufacture of brush products, in particular toothbrushes. Thus, for example, DE-1 028 969 A1 describes a device for feeding bristle tufts in brush manufacturing machines. The tufting device described therein includes a bristle picker which separates a small cluster of bristles from a major supply of bristles in a bristle magazine and transfers it to the tufting tool which anchors the tuft in the brush body together with a fastening anchor or a cramp. The separating of small bristle clusters or tufts is accomplished by providing the picker with a recess which sweeps along the bristle magazine, the recess being filled with bristles from the magazine during this process.
Furthermore, DE-1 938 937 A1 describes a method for manufacturing brushes having in each tuft at least two types of bristle, each type of bristle being supplied separate from the other type, and wherein during a feeding operation the bristles are withdrawn from a magazine and transferred to a tufting tool of a brush manufacturing machine. According to this specification, provision is made for two bristle magazines rectangular in cross section, with suitable bristle pickers sweeping across the magazines' lower ends to pick up the desired bristle clusters.
A solution similar to the one described in DE-1 938 937 A1 for feeding bristles is disclosed in DE-197 34 615 A1. It describes a method and a device for manufacturing a toothbrush bristle carrier equipped with a plurality of bristle tufts.
Finally, DE-1 632 367 A1 discloses a device for feeding bristles or filament bundles to a brush manufacturing machine, said device being also referred to as bristle magazine. The bristle magazine is essentially quadrangular in cross section. The smooth side walls have in their middle region on one side a curvature causing the cross section to taper to form a rectangle with a reduced base area. This area of reduced cross section amounts to about one third of the overall length of the bristle magazine. To effect bristle flow, a hydraulic press acts upon a pusher at the upper end of the bristle magazine. In addition, a conveyor chain is arranged in the bottom area parallel to the longitudinal axis in an attempt to achieve a steady bristle flow. At the lower end a bristle picker picks up the desired number of bristles, transfer ring them to the brush holder.
A schematic representation of the filament flow in the devices known in the art is given in FIG. 2. In this Figure, reference numeral 1 designates the filament feed unit or the bristle magazine. The bristle magazine 1 is of square cross section, having rectangular guide walls 2 as its lateral boundaries. Filaments 4 of precut length are arranged within the rectangular guide walls 2. Arranged at the upper end of the bristle magazine 1 as seen looking in the plane of the drawing is a pusher 3 to which a hydraulic force is applied in the direction of arrow A. It operates to urge the filaments 4 in a downward direction.
Arranged at the lower end of the bristle magazine 1 of FIG. 2 is a bristle picker 6 which is displaceable in a direction perpendicular to the longitudinal axis of the bristle magazine 1. The bristle picker 6 is also designated as picker tooling or picker bar. In operation, the bristle picker 6 moves forward and backward alternately in the directions of arrows B. On its side close to the bristle magazine 1, the bristle picker 6 has recesses 7 for receiving bristles or filaments 11, said recesses 7 being also designated as “tuft eyes”. The filaments 11 received in the recesses 7 form individual bristle tufts intended for fastening to a toothbrush head in a later processing step. Because the bristle clusters are picked up non-symmetrically, the bristle magazine 1 develops dead zones 5 which are also referred to as filament bridging and interrupt the filament flow.
Furthermore, EP-0 972 465 A1 describes a device for manufacturing bristle products of the type initially referred to. As in all the other citations identified, the bristle magazine has at its dispensing end a discharge opening corresponding to the cross section of the bristle magazine, which is closed by the bristle picker. In the citation referred to, the bristle picker is a crescentshaped slide rotary about an axis and having on its closing surface facing the discharge opening one or several recesses for receiving filaments. Here, too, dead zones of the type mentioned in the foregoing develop in the corners of the bristle magazine close to the discharge opening, which interrupt the filament flow.